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Human head transplant is possible

Technical barriers to grafting one person’s head onto another person’s body can now be overcome, says Italian neurosurgeon Dr. Sergio Canavero, a member of the Turin Advanced Neuromodulation Group. In a recent paper published by the medical journal Surgical Neurology International , Dr Sergio Canavero outlines his method for the "Head Anastomosis Venture" — or HEAVEN; a procedure modeled on successful head transplants which have been carried out on Rhesus monkeys in the 1970s in which the patient survived for eight days.


Italian scientist Sergio Canavero believes he has come up with an outline to successfully complete the first human head transplant in history, which could lead to solutions for those suffering from muscular dystrophy or tetraplegics with widespread organ failure.

Head transplants have been attempted since the 1950s, when Russian scientist Vladimir Demikhov experimented with dogs. Twenty years later, American neurosurgeon Robert White conducted a successful head transplant by moving the head of one monkey to the body of another. The monkey lived for several days, but because White could not connect the two spinal cords, the monkey eventually died.

The one problem with these transplants was that scientists were unable to connect the animals’ spinal cords to their donor bodies, leaving them paralyzed below the point of transplant. But, says Canavero, recent advances in re-connecting spinal cords that are surgically severed mean that it should be technically feasible to do it in humans.

Canavero said in an interview,

"Tomorrow is today; what was impossible can happen now."

As Canavero notes in his research paper :

“The greatest technical hurdle to [a head transplant] is of course the reconnection of the donor’s (D)’s and recipients (R)’s spinal cords. It is my contention that the technology only now exists for such linkage…. [S]everal up to now hopeless medical connections might benefit from such a procedure.”

But completing a head transplant is incredibly tedious, and the spinal cord fusion hasn't been tested.

Though the procedure's name suggests otherwise, the recipient would be receiving a new body, not a new head. Both the body-recipient and the body-donor's heads are severed before the recipient's is attached to a new body.



What is the procedure ?

The procedure Canavero outlines is very much like that used by Robert White, who successfully transplanted the head of a rhesus monkey onto the body of a second rhesus in 1970. First, both patients must be in the same operating theater. Then the head to be transplanted must be cooled to between 12°C and 15°C (54.6°F and 59°F). Moving quickly, surgeons must remove both heads at the same time, and re-connect the head to be preserved to the circulatory system of the donor body within one hour. During the reconnection procedure, the donor body must also be chilled, and total cardiac arrest must be induced.

Once the head is reconnected, the heart of the donor body can be re-started, and surgeons can proceed to the re-connections of other vital systems, including the spinal cord.


Connecting the spinal cord is the final barrier !!!

Connection of a spinal cord from the head of one creature to the body of another has never been attempted even in animals, so Canavero’s paper must be taken as an exercise in speculation. However, the severing and re-connection of spinal cords in the same animal has met with limited success in the past. Just this week, scientists at Case Western Reserve University and the Cleveland Clinic were able to restore limited connectivity between the two severed halves of spinal cords in rats.


The re-connection of spinal cords can be accomplished through the encouragement of the body’s natural healing mechanisms, which are at work even in the severed spinal cord. But Canavero’s proposal is different: By cutting spinal cords with an ultra-sharp blades, and then mechanically connecting the spinal cord from one person’s head with another person’s body, a more complete (and immediate) connection could be accomplished.

As he notes in his research paper :

“It is this “clean cut” [which is] the key to spinal cord fusion, in that it allows proximally severed axons to be ‘fused’ with their distal counterparts. This fusion exploits so-called fusogens/sealants….[which] are able to immediately reconstitute (fuse/repair) cell membranes damaged by mechanical injury, independent of any known endogenous sealing mechanism.”

Canavero hypothesizes that plastics like polyethylene glycol (PEG) could be used to accomplish this fusing, citing previous research showing that, for example, in dogs PEG allowed the fusing of severed spinal cords.

Although, Dr Canavero admits that his polymer gel reattachment method (known as GEMINI) would not be perfect . But he notes that: "as little as 10% of descending spinal tracts are sufficient for some voluntary control of locomotion in man."

"PEG is easy to administer and has a strong safety record in man," Canavero says.

Once the spinal cords of the recipient and donor are successfully connected, the body's heart can be restarted, pumping blood into the brain, and "normal temperatures will be reached within minutes."

Canavero says that there is still much work to be done – the spinal cord fusion needs to be tested, and he says he has not addressed the ethical aspects of the procedure.

Though the surgery is primarily intended for people with severe medical conditions, Canavero says it could open the door to a moral dilemma. A head transplant could provide a possible cure for those with conditions that leave the brain functioning while affecting the rest of the body, like progressive muscular dystrophies, or even cancer.

"These are a source of huge suffering, with no cure at hand," Canavero writes.

He says that full and open research on the topic could bear fruit in just two years, and that the first patient should be someone young, with a fully-functioning brain, but suffering from "progressive muscular dystrophies or even several genetic and metabolic disorders".

But people who simply want to cheat death could hypothetically undergo the surgery to acquire a younger body, he says.

"The problem is regulating a procedure that has the power to, I would say, disrupt society," Canavero says.



Courtesy : Various online sources



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